calling the function of one class from another class

[cmpython at gmail.com]

On Sep 24, 2:27 pm, Steve Holden <st... at holdenweb.com> wrote:
> Furkan Kuru wrote:
>
> > On 9/22/07, *Mridula Ramesh* <mridula.c... at gmail.com
> > <mailto:mridula.c... at gmail.com>> wrote:
>
> >     hi.
>
> >     i currently have code structured like this:
>
> >         classA():
> >             def __init__():
> >              ..............
> >              ..............
>
> >             def fnc1():
> >             ....................
> >             ....................
>
> >         classB():
> >            def __init__():
> >             ........................
> >             ........................
> >             classA.fnc1()    #this is where i get an error
>
> >     TypeError: unbound method fnc1() must be called with classA instance
> >     as first argument (got nothing instead)
>
> >     when i do  fnc1(classA) i get:
>
> >     NameError: global name 'fnc1' is not defined
>
> >     am i violating some programming rule by trying to call fnc1 in
> >     classB? i am only now learning OO alongside python, so i'm not sure!
> >     also, can someone please tell me where to go for more articles on
> >     the classes and functions and calling them from other places?
>
> >     thanks a lot!
>
> >     mridula.
>
> >     --
> >    http://mail.python.org/mailman/listinfo/python-list
> >     <http://mail.python.org/mailman/listinfo/python-list>
>
> > you should create an instance of ClassA:
>
> > a = ClassA()
> > a.fnc1()
>
> Unfortunately this won't work either, as calling the method on an
> instance will automatically provide the instance as the first argument
> to the method call, but the method is defined to take no arguments.
>
> > or if you want a static function you should declare the method as static
>
> > classA():
> >     def __init__():
> >      ..............
> >      ..............
> >     @staticmethod
> >     def fnc1():
> >     ....................
> >     ....................
>
> Although most often if you want a static function you should just define
> ... a function!
>
> The OP should read through the tutorial, or at least those sections
> dealing with function and class definitions. It appears (s)he may be
> trying to write Java in Python. That's never a satisfactory experience.

If the OP is not familiar with programming in general the official
Python
tutorial is probably hard to "get".  It's written for other
programmers
from C++ or other languages so they know what is different about
Python.

One way the OP could go is to (and yes this actually is mentioned in
that
section of the tutorial) add "self" to the fnc1 so that when you call
it from within classB the number of arguments--1--match, like:

classA():
    def __init__():
        def fnc1(self):

classB():
    def __init__():
         a = ClassA()
         a.fnc1()

Is there another way without having to add self to fnc1?